Alkylated tertiary amines as high-temperature antioxidants for ester base lubricants

ABSTRACT

This invention is directed to an improved ester base lubricant composition which exhibits enhanced oxidative stability in use. This improved lubricant composition comprises a major amount of an ester of a carboxylic acid and a minor amount of; (a) a mixture of a secondary aromatic amine and a tertiary aromatic amine; or (b) a mixture of two tertiary aromatic amines. Other additives can be included in the improved lubricant composition.

United States Patent [191 Wendler et a1.

ALKYLATED TERTIARY AMINES AS HIGH-TEMPERATURE ANTIOXIDANTS FOR ESTER BASE LUBRICANTS Inventors: Kenneth T. Wendler, Freehold;

David A. Daniels, Kendall Park, both of NJ.

W. R. Grace & C0., New York, NY.

Filed: July 16, 1973 Appl. No.: 379,823

Related US. Application Data Continuation-impart of Ser. No. 362,693, May 22, 1973, abandoned, which is acontinuation of Ser. No.

Assignee:

152,405, June 11, 1971, abandoned.

References Cited UNITED STATES PATENTS 11/1955 Watson 252/46.7

[ Nov. 19, 1974 2,758,086 8/1956 Stuart et a1. 252/32.5 2,930,758 3/1960 Tierney et a1 t 252/46.7 3,231,499 1/1966 Smith 252/565 3,305,483 2/1967 Coffield 252/42.4 3,413,227 11/1968 Howard et a1. 252/5 [.5 3,663,436 5/1972 Carswell 252/28 FOREIGN PATENTS OR APPLICATIONS 793,115 4/1958 Great Britain 252/50 Primary Examiner-W. Cannon Attorney, Agent, or Firm-Elton Fisher; Kenneth E. Prince [57] ABSTRACT This invention is directed to an improved ester base lubricant composition which exhibits enhanced oxidative stability in use. This improved lubricant composition comprises a major amount of an ester of a carboxylic acid and a minor amount of; (a) a mixture of a secondary aromatic amine and a tertiary aromatic amine; or (b) a mixture of two tertiary aromatic amines. Other additives can be included in the improved lubricant composition.

40 Claims, N0 Drawings ALKYLATED TERTIARY AMINES AS HIGH-TEMPERATURE ANTIOXIDANTS FOR ESTER BASE LUBRICANTS CROSS REFERENCE TO RELATED APPLICATION This is a continuation-in-part of our copending application Ser. No. 362,693, filed May 22, 1973 and now abandoned which is a continuation of application Ser. No. 152,405, filed June 11, 1971 and now abandoned.

BACKGROUND OF THE INVENTION The instant invention is directed to an improved lubricant composition based on a lubricant ester (e.g., a lubricant comprising a lubricant ester of a carboxylic acid-especially an ester of an alkanedioic acid). Said improved lubricant composition comprises a major amount of such ester plus a minor amount of; (a) a secondary amine selected as recited infra plus a tertiary amine selected as recited infra; or (b) two tertiary amines selected as recited infra. Said improved lubricant composition exhibits superior oxidative stability at elevated temperatures.

Petroleum oil lubricants have been known to the art for some time and have proven useful for general purpose lubrication. However, petroleum oils have generally been unsatisfactory lubricants in service at temperatures much above 200F to 25020 F because of a tendency of such lubricants to oxidize rapidly. A variety of synthetic lubricants have been developed in the past several decades to deal with high temperature and related lubricant use requirements. The ever increasing development of higher speed and heavier duty military and industrial equipment has produced an ever increasing demand to develop improved lubricants.

Since about 1940, ester base lubricants have been available to the art and have been used with some success for high temperature lubrication. With the development of jet engines and particularly hightemperature jet engines, increasing use has been made of synthetic lubricants based on organic esters of the diester type such as those diesters derived from adipic, azelaic and sebacic acids by esterification with C to C alkanols. An example of a diester fluid which has been a widely used synthetic lubricant is di(2- ethylhexyl) sebacate which has been employed in lubricant formulations known in the art as jet engine oils and related lubricants. However, recent heavy demands and price competition have led to use of a variety of diesters derived from more readily available dicarboxylic acids.

Synthetic ester based lubricant compositions (e.g., an ester base lubricant plus an additive or additives) which include phosphate esters are known to those skilled in the art. These organic phosphorus compounds have the general formula OP(OR) where R represents an aryl or an alkyl group or the like. Improved load carrying capacity and wear protection for gears and ball and roller bearings has been provided by including from about 1 to about 5 weight percent tricresyl phosphate in the lubricant composition of our invention.

Various known synthetic lubricating compositions have often included secondary amines with some success for stabilization against oxidation. Typically, phenothiazine has been included in an amount of about 0.5 weight percent. These compositions have generally included substantial quantities of various expensive materials for use as thickening agents, rust inhibitors and as other special purpose agents. However, many of these known ester based lubricant compositions have not been entirely satisfactory in high temperature service due to rapid oxidation of the lubricant resulting in excessive increase in viscosity with increasing temperature, excessive deposit formation resulting from degradation of the lubricant, high corrosion-induced weight losses for the materials being lubricated and for other reasons. Moreover, many of these otherwise suitable lubricating compositions have not met the recently more stringent oxidative stability and related recently more critical requirements of lubricant users.

U.S. Pat. No. 3,282,840 (Foster, et al, 252/50) teaches a lubricating composition which is a carboxylic acid ester lubricant stabilized with a secondary amine such as diphenylamine, p,p-dioctyldiphenylamine, phenyl-a-naphthylamine, and the like.

U.S. Pat. No. 3,305,483 (Coffield, 252/42.4) teaches the use of certain tertiary amines to stabilize lubricating oil, gear oil, grease, and rubber.

U.S. Pat. No. 3,660,290 (Schloobohm, 252/51.5A) teaches the use of certain 4-alkylphenyl-1-alkyl-2- naphthylamines and mixtures thereof with certain 4- alkyl-phenyl-Z-naphthylamines to improve the oxidation resistance of certain lubricant compositions. Certain other additives including phosphorus extreme pressure agents and a triazole corrosion inhibitor are included in some of the lubricant compositions taught by said patent.

Other patents teaching lubricant compositions based on esters of carboxylic acids include:

1. U.S. Pat. No. 2,758,086 (Stewart,

2. U.S. Pat. No. 3,663,436 (Carswell, 252/28).

3. U.S. Pat. No. 3,413,227 (Howard, et al.,

4. U.S. Pat. No. 2,722,518 (Watson, 252/46.7).

5. U.S. Pat. No. 1,930,758 (Tierney, et al.,

6. British Pat. No. 793,1 15 (Esso Research and Engineering Company).

Ester lubricants (lubricant esters of carboxylic acids) are also taught by the Kirk-Othmer Encyclopedia of Chemical Technology. See Volume 8; page 514 of the first edition and Volume 12, pages 579-5 and Table 10 (on page 578 of the second edition of said Encyclopedia. 1

SUMMARY OF THE INVENTION In summary, this invention is directed to an improvement in a lubricant composition comprising an ester type lubricant (an ester base lubricant, e.g., a lubricant composition comprising a lubricant ester of a carboxylic acid), said improvement comprising the presence of;

a. a secondary amine having the formula;

et al.,

in which R and R are separately alkyl groups having 4-12 carbon atoms; and

b. a tertiary amine having the formula;

in which R is an alkyl group having 4-12 carbon atoms and R R and R are separately selected from the group consisting of CH C H iodine, bromine, chlorine, fluorine, nitro, and hydrogen, A is CCI CBr C1 or an alkylene group having about l-7 carbon atoms, and R is hydrogen or an alkyl group having 4l2 carbon atoms, said secondary amine and said tertiary amine being present in an amount effective for improving oxidative stability of the ester base lubricant at temperatures up to at least 400F.

The amount of said amines present in the ester base lubricant is not critical and a finite amount produces a finite improvement; however, we generally prefer to have about 0.5-8 (preferably 0.5-7) parts of said secondary amine and 05-10 (preferably 0.5-8) parts of said tertiary amine present per 100 parts of said ester.

DESCRIPTION OF PREFERRED EMBODIMENTS In a preferred embodiment (Embodiment A) this invention is directed to an improvement in a lubricant composition comprising an ester type lubricant (an ester base lubricant, e.g., a lubricant composition comprising a lubricant ester of a carboxylic acid), said improvement comprising the presence of;

(a) a first tertiary amine having the formula in which R, and R are separately alkyl groups having 4l2 carbon atoms and R R and R are separately selected from the group consisting of CH C H iodine, bromine, chlorine, fluorine, nitro, and hydrogen, and A is C Cl CBr C1 or an alkylene group having about l-7 carbon atoms, and

b. a second tertiary amine selected from the group consisting of tertiary amines having the formula N I I -R&

| in A I R&

in which R is an alkyl group having 4-12 carbon atoms and R R and R are separately selected from the group consisting of CH C H iodine, bromine, chlorine, fluorine, nitro, and hydrogen, and A is CCl CBr Cl or an alkylene group having about l-7 carbon atoms, and R is hydrogen or an alkyl group having 4l2 carbon atoms, said first tertiary amine and said second tertiary amine being present in an amount effective for improving oxidative stability of the ester base lubricant at temperatures up to at least 400F. The amount of said amines present in the ester base lubricant is not critical and a finite amount produces a finite improvement; however, we generally prefer to have about 0.5-10 parts of said second tertiary amine present per parts of said ester (the lubricant ester of the carboxylic acid), and we generally prefer a weight ratio of first tertiary amine to second tertiary amine of about 122-4.

In another preferred embodiment (Embodiment a-l this invention is directed to an improvement in a lubricant composition comprising an ester type lubricant (an ester base lubricant, e.g., a lubricant composition comprising a lubricant ester of carboxylic acid), said improvement comprising the presence of;

a. a secondary amine having the formula;

i II in which R, and R are separately alkyl groups having 4-12 carbon atoms and R R and R are separately selected from the group consisting of c11 C H iodine, bromine, chlorine, fluorine, nitro, and hydrogen, A is CC1 CBr C1 or an alkylene group having about 1-7 carbon atoms, said secondary amine and said tertiary amine being present in an amount effective for improving oxidative stability of the ester base lubricant at temperatures up to at least 400F.

In preferred embodiments of; (a) the embodiment (lubricant composition) set forth in the above Summary; and (b) the embodiments (i.e., the lubricant composition) set forth in Embodiments A and A-1, su-

pra: 1

1. R R and R are alkyl groups having 8 carbon atoms and are more preferably alkyl groups having the formula C(CH CH C(CH or CH C(CH C(C1-1 2. R R and R are alkyl groups having 8 carbon atoms and are more preferably alkyl groups having the formula C(CH C1-1 C(CH or CH C(CH C(CH 3. The lubricant composition contains 0-10 (preferably 0.5-10) parts of a phosphorus-containing ester per parts of the lubricant ester of a carboxylic acid. Preferred phosphorus-containing esters are triesterified phosphoric acid components derived from a hydroxy compound selected from the group consisting of straight and branched chain alcohols having from 1 to about 8 carbon atoms, phenol, cresols, xylenols, and alkyl substituted naphthols in which the alkyl groups each have 1-10 carbon atoms in straight or branched chain configuration, and the number of alkyl groups is 1-3. Especially preferred phosphorus-containing acid esters include tricresyl phosphate, triphenyl phosphate, cresyldiphenyl phosphate, xylyldiphenyl phosphate, triethyl phosphate, tributyl phosphate, and triisooctyl phosphate. 4. The lubricant composition includes, or contains, 0 to 1 part, per 100 parts of the lubricant, of an amino substituted 1,2,4-triazole component, benzotriazole, 5,5-methylene-bis-( 1,2,3-Ibenzotriazo1e), or an alkyl benezotriazole in which the .alkyl group contains about 1-12 carbon atoms.

5. The carboxylic acid ester component of the lubri cant composition is acid ester component is a diester having the general formula R OOC(CH ),,COOR wherein n is an integer from 2-30 and R and R are separately selected from the group consisting of straight and branched chain alkyl groups containing from 6-16 carbon atoms. It is especially preferred that R and R are separately selected from the group consisting of straight and branched chain octy] and tridecyl groups and n is 4-8. R and R can be identical.

6. The carboxylic acid ester component of the lubricant composition is an ester derived from aliphatic carboxylic acids having 3-18 carbon atoms and polyols selecting from the group consisting of trimethylolpropane, pentaerylthritol, dipentaerythritol, tripentaerythritol and neopentylglycol.

In especially preferred embodiments of our invention as recited in the above Summary:

1. The secondary amine can be selected from: 4,4- 1,1,3,3-tetramethylbutyl)-dipheny1amine, N-4- 1,1,3 ,3-tetramethylbutyl )-phenyl-a-naphthylamine, N-4-( 1 ,1 ,3,3-tetramethy1buty1)-phenyl-B- naphthylamine, and N-4-( l ,1,3,3-tetramethy1buty1)- pheny1-1-( 1 ,1 ,3,3-tetramethylbutyl )-B-naphthy1amine.

2. The tertiary amine can be selected from: N,N-bis- 4-(1,1,3,3-tetramethy1buty1)-phen y1benzy1amine, N,N- bis-4-( 1,1 ,3,3-tetramethylbutyl)-p1henyl'2' phenylethylamine, N,N-bis-4-( 1,1,3,3- tetramethylbutyl)-phenyl-2-methylbenzylamine, N,N- bis-4-(1,1,3,3-tetramethylbuty1)-pheny1-4- methylbenzylamine, N,N-bis-4( 1,1 ,3,3- tetramethylbutyl)-pheny1-2-chlorobenzy1amine, N,N- bis-4-( 1,1,3,3-tetramethy1buty1)-phenyl-4- chlorobenzylamine, N,N-bis-4-( 1,1 ,3,3- tetramethylbutyl)-phenyl-2,4-dich1orobenzylamine, N,N-bis-4-( 1 l ,3,3-tetramethy1but.y1)-pheny1-3,4- dichlorobenzylamine, N,N-bis-4-( 1,1,3,3- tetramethylbutyl)-phenyl-aa-dich1orobenzylamine, N,- N-bis-4-( 1 ,1 ,3,3-tetramethylbutyl)-pheny1-2- fluorobenzylamine, N,N-bis-4-( 1 ,1 ,3,3- tetramethylbutyl)-pheny1-4-fluorobenzylamine, N,N- bis-4-( 1 ,1 ,3,3-tetramethylbutyl)-pheny1- 4nitrobenzylamine, N,N-bis-4-( 1,1,3,3- tetramethylbutyl)-phenyl-2,2-dimethyl-2- phenylethylamine, N-4-( 1 ,1 ,3,3-tetramethylbuty1)- phenyl-N-a-naphthylbenzylamine, N-4-( 1,1,3,3

mine, and N-4-( l ,l ,3,3-tetramethylbutyl)-phenyl- N-B-naphthylbenzylamine; and

e. -0.5 parts of a member selected from a third group consisting of an amino-1,2,4-triazole, benzotriazole, ,5-methylene-bis-( 1,2,3-benzotifiazole), and an alkyl benzotriazole in which the alkyl group preferably has 1-12 carbon atoms.

In another preferred embodiment (Embodiment C") this invention is directed to:

A lubricant composition comprising:

a. 100 parts of a carboxylic acid ester;

b. 0.5- parts of tricresyl phosphate;

c. 0.5-8 parts of a secondary amine selected from a first group consisting of N-4-(l,1,3,3- tetramethylbutyl)phenyl-a-naphthylamine, and N- 4-( 1,1,3 ,3-tetramethylbutyl )phenyl-B- naphthylamine;

d. 0.5-10 parts of N,N-bis-4( l,l,3,3-tetramethylbutyl) phenyl-benzylamine; and

e. OO.5 parts of a member selected from a third group consisting of an amino-1,2,4triazole, 5,5- methylene-bis-(1,2,3-benzotriazole), and an alkyl benzotriazole in which the alkyl group preferably has l-l2 carbon atoms.

DETAILED DESCRIPTION OF THE INVENTION It has now been found by practice of the present invention that there is provided a new improved ester base lubricant composition by including a secondary aromatic amine component having two aromatic groups attached to the nitrogen atom and a small amount of alkylated tertiary amine having at least two aromatic groups attached to the nitrogen atom of said amine in the ester base lubricant. In use, the present lu bricant composition exhibits improved oxidative stabil ity not only at moderate use temperature, but also at high temperatures (i.e., about 250F to about 400F and higher), and metals and related materials lubricated by the composition of this invention often show increased service life, decreased wear, and less corrosion. This lubricant is further advantageously characterized as having decreased sensitivity to form harmful deposits with increasingly excellent lubricating performance under more stringent testing conditions recently adopted by lubricant users. The present composition and method for using said composition offer improved lubricating performance relative' to related compositions and methods of the prior art, while providing the art with a means to meet many of the ever increasing lubricant performance requirements of super-sonic jet aircraft and the like.

Generally speaking the present lubricating composition (lubricant composition) includes a major portion of a carboxylic acid ester component having good lubricating (lubricant) qualities, a minor amount of a secondary aromatic amine component and a minor amount of a tertiary aromatic amine component, said amines, being selected according to the teachings of the Summary or Embodiments A and A-1 supra.

Alternatively, the lubricant (lubricating) composition of this invention includes a major portion of a carboxylic acid ester component having good lubricant (lubricating) qualities and a minor amount of each of two tertiary amines as recited in Embodiment A, supra.

The lubricant composition of this invention can include other additives (among such additives are esters W of phosphoric acid, detergents, viscosity index improves, extreme pressure additives, rust inhibitors, and the like which like carboxylic ester lubricants -are well known in the art).

The carboxylic acid ester component of the present lubricant composition may be almost any carboxylic acid ester having good lubricating qualities. Typically, this ester component is a diester having the general formula R OOC(CH ),,COOR wherein n is an integer from about 2 to about 30 and R and R are members selected from the group consisting of straight and branched chain alkyl groups having from about 6 to about 20 carbon atoms. Preferably, n is an integer from about 4 to about 8 and R and R are selected from straight and branched chain alkyl groups having 8-l6 carbon atoms.

A preferred class of esters from which the carboxylic acid ester component may be selected includes those esters derived from aliphatic monocarboxylic acids by esterifying these acids with polyols, i.e., aliphatic alcohols having 2 or more hydroxy groups. Aliphatic monocarboxylic acids which have from about 3 to about 18, and preferably from about 4 to about 12 carbon atoms are useful. Suitable polyols include, to name a few, trimethylolpropane, pentaerythritol, neopentyl glycol, dipentaerythritol, tripentaerythritol and mixtures thereof. Exemplary esters of this class include pentaerythrityl tetrabutyrate, pentaerythrityl tetracaproate, pentaerythrityl dibutyrate-dicaproate, mixed C, to C saturated fatty acid esters of pentaerythritol, dipentaerythrityl mixed hexaesters of C 10 C fatty acids, trimethylolpropane trioctanoate and the like.

Another class of esters which may be included in the present lubricant composition are: aliphatic polyesters having the following general formula:

Wherein R is an alkyl group having from 1 to about 12 carbon atoms, and preferably from about 5 to about l2 carbon atoms. R,, is an alkylene group having from about 2 to about 34 carbon atoms in straight or branched chain configuration. R is an alkylene or oxyalkylene group having from about 2 to about 20 carbon atoms. These polyesters can be prepared, for example, by esterifying two moles of an alkanedioic acid per mole of glycol, followed by esterif 'ying the resulting diester product with two moles of alkanol per mole of the product.

The ester component of the present lubricant composition can include mixtures of the above-described carboxylic acid esters. Typically, the composition includes the ester component in a major amount.

The secondary aromatic amine component of the present lubricant can be selected from those secondary amines having two aromatic groups attached to a nitrogen atom of the amine. The aromatic groups can be heterocyclic or homocyclic, as desired. The aromatic groups of the amine component can have the same or different formulas, as desired. Exemplary of aromatic amines suitable herein are, to name a few, phenyl-anaphthylamine, diphenylamine, phenyl-B- naphthylamine, and preferably the alkyl substituted derivatives of these compounds. Typically, the aromatic groups areidentical to each other and include alkyl The tertiary amine component of the present lubricant can be represented by the following general formula wherein R and R, are aryl groups and R is an aralkyl group suchthat at least one of said R, R, and R contains an alkyl group having l-l2 carbon atoms.

The tertiary amines used in the lubricating composition of this invention can be prepared in good quantity and in the relatively pure state as disclosed in copending application U.S. Ser. No. 152,372, filed June 11,

i 1971, now abandoned and assigned to W. R. Grace and Co. when a secondary amine having the formula where R is an aryl group and R, is an aryl group which may be the same as R, is reacted with sodium hydride in the-presence of dimethylsulfoxide (DMSO) and the product of this reaction is reacted with an aralkyl halide compound such as benzyl chloride, benzyl bromide, benzyl iodide, l-bromo-S-phenylpropane, l chloro-4- phenyl-n-butane, or the like to form the desired tertiary amine which is recovered. Preferably R and R, are aryl groups having 6- l 2 carbon atoms, at least one group of which contains a halo, nitro, hydroxy, aryl, alkyl or the like group.

The final tertiary amine anti-oxidant which is obtained when an aralkyl halide compound, is reacted with an aromatic secondary amine is represented by the general formula:

wherein R is an aralkyl radical having 7-22 carbon atoms and R and R, are separately selected from a group consisting of an aryl group having 6-22 carbon atoms and an alkaryl group having 7-22 carbon atoms such that at least one of R and R, is an alkaryl radical having 7-22 carbon atoms. R, can contain at least one of the following: halo, nitro, hydroxy, alkyl alkoxy, aryl, or the like. Preparation of tertiary amines used in the instant invention is described in copending US. Pat. application Ser. No. 379,835, filed 7 /l6/73; which is assigned to W. R. Grace and Co, and which is a continuation-in-part of US. Pat. application Ser. No. 152,372, filed June 11,- 1972, and now abandoned which is also assigned to W, R. Grace and Co.

The aralkyl halide compound which is used in this invention is preferably benzyl chloride, a substituted benzyl chloride or an aralkyl halide. For example those aralkyl halides having the following general formula are operable:

wherein n is an integer in the range of 06, A, B, F, D, E, G, I, J, K, L, M, and N are members of the group selected from hydrogen, halo, nitro, hydroxy, alkyl, and alkoxy groups, X is either chlorine or bromine, R is either hydrogen or a methyl group and R is either hydrogen or a methyl group. Preferably the alkyl and alkoxy groups have l-l2 carbon atoms.

Some of the tertiary amines which can be prepared and used herein are, more particularly, represented by the following:

wherein R,,, R R13 and R may be hydrogen, an alkyl or alkoxy groups having l-l2 carbon atoms, an aryl group containing 6-22 carbon atoms, or a halo, nitro, or the like group such that at least one of said R,,, R12, R and R, is said alkyl group, R R R R and R may be hydrogen, an alkyl or alkoxy group having l-l2 carabon atoms, or a halo. nitro, or the like group, n is an integer from 0-6, R is either hydrogen or a methyl group and R is either hydrogen or a methyl group;

Wherein R R R R and R are hydrogen, an alkyl or alkoxy group containing 1-12 carbon atoms, or halo, nitro, or the like groups, R is an alkyl or alkoxy group containing 1-12 carbon atoms and n is an integer from 0-6. R is either hydrogen or a methyl group and R is either hydrogen or a methyl group; and 20 N,N-bis-4-( 1 ,1 ,3,3-tetramethylbutyl)phenyl-3,4-

dichlorobenzylamine,

N,N-bis-4-( 1 ,1 ,3,3-tetramethylbutyl)phenyl-2,4-

dichlorobenzylamine,

N,N-bis-4-( 1 ,1,3,3-tetramethylbuty1)phenyl-2- methylbenzylamine,

N,N-bis-4-( 1,1 ,3,3-tetramethylbutyl )pheny1-2- chlorobenzylamine, (1:11,) N,N-bis-4-( 1,1 ,3,3-tetramethylbutyl)phenyl-4- bromobenzylamine,

RP N,N-bis-4-( 1,1,3,3-tetramethy1brutyl)phenyl-aa- R dichlorobenzylamine,

Raw My N,N-bis-4-(1,l,3,3-tetramethylblutyl)phenyl-4- nitrobenzylamine,

on; 0113 Where R 1, R R R and R are hydrogen, 35 WCIIZ--(II(IZ-CIIJ an alkyl or alkoxy group having 1-12 carbon atoms, or i E halo, nitro, or the like groups, R is an alkyl or alkoxy group containing 1-12 carbon atoms, R, is hydrogen, f an alkyl or alkoxy group containing l-12 carbon cm atoms, an aryl group containing 6l0 carbon atoms, or I halo, nitro, or the like groups, n is an integer from 06,

R is either hydrogen or a methyl group and R is either hydrogen or a methyl group. The choice of which secondary aromatic amine is to be used is, of course, de- I pendent upon which tertiary amine is desired. For ex- E1;3$3friziifiLiRlflllli?$3,;m ample, to prepare N,N-bis-4-(1,l,3,3 tetramethylbutyl- )phenylbenzylamine, the secondary amine is 4,4-(1,l,3,3 tetramethylbutyl)-diphenylamine, and to prepare N,N-bis-4-(2,2,3,3 tetramethylbutyl)phenylbenzylamine, the secondary amine is 4,4'-(2,2,3,3 tetramethylbutyl)-diphenylamine.

Tertiary amines which are especially useful in the lubricating composition of this invention include the fol- 1, CH1 lowing: g --cm o cm 2 cm cm N -a-naphthylbenzylamino N,N-bis-4-( 2,2,3,3-tetramethylbutyl)phenyl-3,4-

dichlorobenzylarnme, N 4 1'133mrmmmylbmyl) N,N-bis-4-( 2,2,3 ,3-tetramethylbutyl )phenyl-2,4- pl1onyl-N-B-naphthylbenzylamino dichlorobenzylamme,

N,N-bis-4-(2,2,3,3-tetramethylbutyl)phenyl-2- methylbenzylamine, N,N-bis-4-(2,2,3,3-tetramethylbutyl)phenyl-2- chlorobenzylamine, N,N-bis-4-(2,2,3,3-tetramethylbutyl)phenyl-4- bromobenzylamine, N,N-bis-4-(2,2,3,3-tetramethylbutyl)phenyl-a-adichlorobenzylamine, and N,N-bis-4-( 2,2,3 ,S-tetramethylbutyl )phenyl-4- nitrobenzylamine. More particularly the process of preparing the tertiary amines used herein which should be followed to obtain optimum results is as follows: dimethylsulfoxide is'heated to a temperature of about 60C. To this is added the sodium hydride. The NaH is preferably added in an amount such that the mole ratio of later added secondary amine to sodium (as Na) added as NaH is about 111.1. In many of the examples a 60% by weight dispersion of sodium hydride in mineral oil was used since it is a common way of obtaining sodium hydride commercially. The amount of dimethylsulfoxide used in the reaction is dependent on the molecular weight of the secondary aromatic amine which is used. A 1:1 mole ratio is operable and has produced excellent results, but generally about 0.5 mole excess dimethylsulfoxide is used to assure complete reaction. Following the addition of the sodium hydride the solution generally turns slightly orange with the evolution of hydrogen. After all gas evolution has stopped, the reaction mixture is agitated for sufficient time (about hour) to attain a complete reaction mixture and the desired secondary aromatic amine is added. Addition of the secondary aromatic amine to the reaction flask normally results in a small exotherm reaction. Therefore, to assure sufficient control of the reaction it is preferable to keep the reaction mixture s temperature below 100C. by adding the secondary aromatic amine slowly, and cooling if necessary. After adding the secondary amine the reaction mixture is agitated (e.g., stirred) forabout 2 hours. The desired aralkyl halide is then added. The mole ratio of secondary aromatic amine to aralkyl halide is also about 1:1. The reaction temperature should not be allowed to exceed 100C; hence; the aralkyl halide is added slowly. This reaction mixture is then agitated to assure substantial complete reaction (about 6 hours at 90100C) and the reaction is then terminated by adding water cautiously, e.g., dropwise.

The reaction mixture (following addition of the water) is a viscous oil. Toluene is added to the viscous oil to form a workable solution and to this solution NaH- CO is added. Said workable solution is washed with water until substantially neutral. The remaining solvents can be removed under vacuum at about 150C. The resulting tertiary amine is then cooled to about 100C and poured into suitable containers for future use. Conversions (one pass yields) by the procedure described herein are about 90-95% of theoretical, and product purity is 96-98%.

However, if the process is deviated from, yield and purity are both noticeably affected. For example, if the secondary aromatic amine is added to the dimethylsulfoxide before the addition of the sodium hydride, the conversion is about 80-85% of theory and product purity is only 78-90%.

The tertiary amine component of our lubricant composition cooperates with the secondary aromatic amine component of our lubricant composition to impart a significant portion of the improved oxidative stability of the present lubricant composition. The tertiary amine component can be included in the composition in an amount from about 0.5 to about 10 parts by weight, and preferably from about 0.5 to about 4 parts by weight based on 100 parts by weight of the carboxylic acid ester component.

The advantageous, although optional triazole component of the present lubricant is an amino substituted triazole compound, and can be selected from 3-aminoand 4-aminol ,2,4-triazole, 5,5-methylene-bis-( l ,2,3- benzotriazole), or alternate corrosion inhibitors such as l ,2,3-benzotriazole or alkyl substituted 1,2,3- benzotriazoles. The triazole component can be included in the present composition in an amount of from 0.002 to about 1 part by weight, and preferably from about 0.01 to about 0.2 part by weight based on 100 parts by weight of the carboxylic acid ester component. The preferred amount'of triazole is limited only by additive solubility and the users requirements.

The advantageously, although optionally, included phosphorus-containing acid ester component can be selected from triesters of phosphoric acid with alcohols such as straight and branched chain aliphatic alcohols having from 1 to about 8 carbon atoms. Exemplary of these esters are triethyl phosphate, tributyl phosphate and triisooctyl phosphate. Other suitable phosphoric acid esters include esters of phenol, cresols, and naphthols, and the like, these esters can have from 1 to about 3 C to C alkyl substituents on one or more of the aryl moieties. Exemplary of these esters are tricresyl phosphate, triphenyl phosphate, cresyldiphenyl phosphate, xylyldiphenyl phosphate, and the like.

The phosphorus-containing acid ester component may be included in an amount rrom 0 to about l0 parts by weight, and preferably from about 0.5 to about 5 parts by weight per 100 parts by weight of the caroboxylic acid ester component.

The present lubricant composition can further include metal deactivating agents, anti-corrosion agents, anti-rusting agents, anti-foaming agents, dyes, thickening agents, additional anti-oxidants and other suitable agents known in the art for use in ester-containing lubricants.

We have found that; (a) the amount of amines present in the improved ester base lubricants of our invention is not critical and a finite amount of the amines produces a finite improvement in the oxidative stability of the lubricants; and (b) this is true whether the amines are; (i) a secondary amine and a tertiary amine selected as recited in the Summary or Embodiment A-l, supra; or (ii) two tertiary amines selected as recited in Embodiment A, supra.

The present invention will be further illustrated by the following non-limiting examples.

Examples 1-37 describe the preparation of the tertiary amine component of this invention.

EXAMPLE 1 To a reaction flask (4-neck, 3 liter flask equipped with a condenser, stirrer, N inlet, thermometer and dropping funnel) containing 1.5 moles of dimethysulfoxide (DMSO) which had been heated to about C was added 1.1 mole of a 60% by weight dispersion of sodium hydride in mineral oil. The solution was observed to turn slightly orange as the sodium hydride was added. After all hydrogen evolution had stopped, the reaction mixture was stirred for one-half hour and then 1 mole 4,4-(1,1,3,3-tetramethylbutyl)- diphenylamine was added to the reaction flask dropwise. The reaction mass was stirred for about 2 hours following which 1 mole of benzyl chloride was added dropwise using a dropping funnel. The reaction temperature was thereby maintained between 6070?C. Following addition of the benzyl halide the reaction tetramethyl)-diphenylamine and the product tertiary amine was N,N-bis-4-(2,2,3,3-tetramethylbutyl)- phenylbenzylamine.

Examples 2-9 Examples 2 through 9 followed the procedure of Example 1 except that the appropriate benzyl compound was added to the 4,4-(1,1,3,3-tetramethylbutyl)dimixture was stirred for 6 hours at a temperature of 10 phenylarnine in order to prepare the tertiary amine dent)" 70F 7.00 ml. of water was cautiously added droprivatives shown in Table 1.

Table l Henxyl (.nmpuund Used Tertiary Amine Obtained benzotrichloride 4-nitrobenzyl chloride 3.4dichlorubenzyl chloride 2.4-dichlorobenzyl chloride 2-methylbenzyl chloride 2-chlorobenzyl chloride 4-bromobenzyl bromide Z-ethylbenzyl chloride wise to terminate the reaction. The viscous oil in the reaction flask was then extracted with 400 ml. of toluene and washed once with 200 ml. of a 10% by weight NaHCO solution. The solution was washed several more times with 200 ml. aliquots of water until the washings were neutral. The remaining solvents and vol- Examples 2A-9A Examples 2 through 9 followed the procedure of Example lA except that the appropriate benzyl compound was added to the 4,4'-('2,2,3,3-tetramethylbutyl)diphenylamine in order to prepare the tertiary atiles were removed under vacuum at 65C. The resultamine e ati es Shown in Table 1A.

Table l -A Benzyl Compound Used Tertiary Amine Obtained Example No.

2 3.4-dichlorobenzyl chloride 3 2,4-dichlorobenzyl chloride 4 Z-methylbenzyl chloride bcnzotrichloride 2-chlorobenzyl chloride 4-bromobenzyl bromide l ethylbenzyl chloride 4-nitrobenzyl chloride N.N-bis-4-( 2.2.3.3-tetrumethylbutyl )phenyl- 3.4-dichlorobenzylamine N.N-bis-4'( 2.2.3.3-tetramethylbutyl )phenyl- 2.4-dichlorobenzylamine N.N-bis-4-( 2.2.3.3-tetrumethylbutyl )phenyl- 2-methylbenzylamine N.N-bis-4-( 2.2.3.S-tetramethylbutyl )phenyl- 2-chlorohenzylamine N.N-bis-4-( 2.2.3 .B-Ietramelhylbutyl )phenyl- 4'bromobenzylumine N.N-bis-4-( 2.2.3 .3-tetramethylbutyl )phenyl- Z-ethyIbenzyIumine N,N-bis-4-( 2.2.3 .3-tetramethylbutyl )phenyldichlorobenzylamine N.N-bis-4-( 2.2.3.3-tetramethylbutyl )phenyl- 4-nitr0benzylamine Example 1A The general procedure of Example 1, was repeated; however, in this instance the 4,4-( l ,l ,3,3-tetramethylbutyl)-diphenylamine was replaced with 4,4-(2,2,3,3-

Examples 10-18 Examples 1-9 were repeated except that 1 mole of N-4-( 1,1,3,3-tetramethylbutyl)phenyl-anaphthylamine was substituted for the 1 mole of 4,4- (1,1,3,3-tetramethylbutyl)-diphenylamine. In each example the appropriate tertiary amine was obtained in good yield and at high purity.

Examples 19-27 Examples l9 were repeated except that 1 mole of N-4-( 1,1,3,3-tetramethylbutyl)phenyl-a- 5 naphthylamine was substituted for the 1 mole of 4,4- (l,1,3,3-tetramethylbutyl)-diphenylamine. In each example the appropriate tertiary amine was obtained in good yield and at high purity.

Examples 28-36 Example 1 was repeated except that 1 mole of N-4- naphthylamine was substituted for the 1 mole of 4,4- (I,1,3,3-tetramethylbutyl)-diphenylamine. In each example the appropriate tertiary amine was obtained in good yield and at high purity.

Examples 38-46 Examples 38-46 illustrate the effect of a 400F 72 Hour Corrosion Oxidation Test on prior art ester base lubricants compositions.

In said test a 0.032 inch X 1 inch X 1 inch metal test specimen is placed in a glass tube and 100 ml of a liquid lubricant composition to be tested is placed in the glass tube to cover the test specimen, and the sample (test speciman plus composition to-be tested) is heated to and maintained at a substantially constant temperature of about 400C while passing 5 liters of clean dry air through the lubricant composition for 72 hours.

The metals used in these tests included magnesium, aluminum, iron, copper and electrolytic grade silver. At the end of a 72 hour testing period, the air flow was terminated and the metal test squares were removed from the compositions, washed in 135F 1,1,1- trichloroethane, air dried, and thereafter weighed. Metal weight changes from before to after testing, ex-

protective coating which is occasionally formed on the individual test specimens.

The test included also measuring kinematic viscosity at 100F of the various compositions tested, before and after testing, using the procedure of ASTM Standard D 445. The results are given below in Table 2 as percent increase in viscosity. Acid value changes (the difference in acid value after and before running the 72 Hour Corrosion Oxidation Test) were also run on each lubricant composition tested. The acid value changes are also shown in Table 2. The acid values used for calculating the changes were measured by potentiometric titration with potassium hydroxide to an end point of pH 1 1 using the procedure of ASTM Standard D 664. The compositions were observed and rated for sludge content at the end of the 72 Hour Oxidation Corrosion Tests. A sludge rating of nil means essentially no sludge was observed, ratings of light, moderate, heavy, etc. were assigned for increasing amounts of observed sludge).

In each of Examples 38-42 the composition tested comprised an ester base lubricant component, a secondary aromatic amine, a phosphorus-containing ester, and an amino substituted, 1,2,4-triazole component. Each composition is unacceptable because of a high acid number change, a viscosity change, or a presence of sludge. Acceptable values are as follows:

Acid No. Change 2.0 or less Viscosity Change 25% or less Visual Sludge Rating Nil In Examples 43-46 the composition contained two different secondary amines. Although improved results (as compared with Examples 38-42) were obtained, the compositions used in Examples 43-46 were also unacceptable because of sludge formation.

Table 2 RESULTS OF 400F, 72 HOUR CORROSION-OXIDATION TESTS COMPOSITION PARTS BY WEIGHT Example No. 38 39 40 41 42 43 44 45 46 Carboxylic Acid Ester I00 I00 100 100 100 100 I00 100 PhenyI-a-nap'th lamine 1.0 1.0 PhenyI-fl-napht ylamine 1.0 1.0 4,4-( I .I ,3.3-tetramethylbutyl)- diphenylamine 2.0 2.0 2.0 2.0 2.0 N-4-( I .l ,3.3-tetramethylbutyl phenyI-a-naphthylamine I 5 1.5 N-4-( I ,I,3,3-tetrumethylbutyl phenyI-flmaphthylamine 1.5 1.5 Tricresyl phosphate 10 1.0 1.0 1.0 1.0 I 0 1.0 I 0 1.0 3-amino-l ,2.4-triazole 0.05 0.05 0.05 0.05 0.05 0 05 0.05 0 05 0.05

Corrosion, mg/cm 4 Magnesium 0.000 -0.0I0 0.405 0.023 0.1 17 0.039 ().085 +0.03I 0.023 Aluminum 0.0I5 +0.0l0 +0.0I5 0.023 0.101 ().023 0.039 +0.015 -0.03I Copper 0.03l 0.046 0.0l0 0.039 0.046 -0.078 0.039 0.023 0.070 Iron 0.015 +0.010 +0023 0.023 0.078 0.015 0.023 +0.015 0.010 Silver 0.03l 0.0IO 0.023 0.054 0.062 0.163 0.078 +0.015 -0.054

Total Acid No. Change, mg KOH/g 2.50 5.50 8.20 1.14 3.67 0.65 0.72 0.57 0.72

Viscosity Change (100F), 24.8 40.0 44.8 14.2 36.0 19.0 18.3 v 18.0 18.6

Visual Sludge Rating Heavy Heavy Heavy Moderate Moder. Moder. Moder. Light Light "The compositions tested in Examples 38-46 and reported in this table are prior art compositionsnnt the compositions of this invention. "A technical pentrucrythritol estcr made from C C and C straight chain mopocarboxyl acids.

pressed in milligrams per square centimeter of metal surface, are shown below in Table 2 for various lubricant compositions. The figures are caused by a The following examples shown the effect of using an alkylated tertiary amine as part of the lubricant composition to improve stability and resistance to oxidation.

Examples. 47-60 The compositions prepared as shown in Table 3 were subjected to the 400F., 72 Hour Corrosion Oxidation Examples 47-60 are summarized in Table 3. Results shown in this table illustrate the improvement obtained with the additives of this invention.

TABLE 3 Results of 400 F., 72 hour corrosion-oxidation tests diphenylamine N4-(1.1.3.3-tetramethylbutyl) phenyl-a-naphthylamine N-4-(1,1,3.3-tetrameth ylhutyD- thylam' 'Irioresyl B-amin 1 Crrosion,1ng./c Magnesium Aluminium -0. 023 Total acid No. change, 7 mgJKOH/g 0. 66 Viscosity change (100 F.), percent Visual sludge rating.

18. 6 Nil Parts by weight n The composition of Examples 51-60 are compositions of the instant invention. I b A technical pentaerythritol ester made from C C1, and Ca straight chain monoearboxylic acids.

Test described in Examples 38-46.

The ester base lubricant used in Examples 47-60 was a technical pentaerythritol ester made from C C and C straight chain alkanoic acids. Said ester was from the same lot that was used in Examples 38-46.

The compositions tested in Examples 47-50 were the ester base lubricant plus the following additives; (a) one tertiary amine; (b) a phosphorus containing ester; and (c) a 1,2,4-triaz0le component. Although sludge formation was light (L), the acid number and viscosity changes were such that these lubricant compositions (those tested in Examples 48-50) were unacceptable.

In Examples 51-56 various secondary aromatic amines were added to the compositions of Examples 47-50 so that the lubricant composition now, contained both a secondary amine and an alkylated tertiary amine. In each example the sludge formed was nill (N), and improved, acceptable acid numbers and viscosity changes were obtained.

In Examples 57-60 the lubricant composition contained no secondary amine, but two alkylated tertiary amines. Acceptable results were obtained in each of these examples.

' The change in the acidity of the composition being tested before and after the 72 Hour Corrosion Oxidation Test measured by potentiometric titration with potassium hydroxide to an end point of pH 1 I using the procedure of ASTM Standard D664.

2 The increase in viscosity as determined by measuring the viscosity of the composition before the 72 Hour Corrosion Oxidation Test and then after said test using the procedure of ASTM Standard D445.

it has also been found that results superior to those attained heretofore are obtained when two different tertiary amines are added to the base stock (carboxylic acid ester lubricant) instead of a secondary and a tertiary amine.

Generally, as shown in Table 3, results of the 72 Hour Corrosion Oxidation Tests show that when two alkylated tertiary amines are used to prepare the composition (Examples 57, 58, 59 and 60), there is a marked reduction in sludge formation and an obvious improvement in oxidation stability.

Examples 61-64 In Examples 61-64 Alcor deposition tests of various ester base lubricant compositions with the antioxidants of Table 3 are shown. These tests were conducted to show the effectiveness of the additives in controlling oxidation stability and deposition (cleanliness). In each example 100 parts'by weight of atypical lubricant ester base stock and 1 part by weight of a phosphoruscontaining ester (tricresyl phosphate) were used. In Example 61 the additive was a secondary amine; in Example 62 the additive was an alkylated secondary amine; in Example 63 the additive was an alkylated tertiary amine; and in Example 64 the additive was a combination of two alkylated tertiary amines.

In Examples 61-64 the compositions described were submitted to the Alcor High Temperature Deposition Tests. In this test, the purpose of which is to determine cleanliness and oxidation stability of the lubricant being tested, the following test procedure is used. The lubricating composition being tested is circulated through an Alcor Deposition Tester, Model HTDT 1003, manufactured by Alcor, Inc., of San Antonia,

Tex. at 300 ml/min. by a high temperature pump. Constant flow is maintained by a constant speed drive. The composition is then heated to a specified temperatures, in this instance 500F. Any sludge which is formed is collected on a filter screen and weighed. Ideally, the deposits would be nil, however, the results shown for Examples 63 and 64 are quite acceptable. There is also a formation of deposits on the tube which is being heated. Heat was supplied by an electric current passed through the metal tube. The composition being tested is circulated past the heated tube. The deposits are recognized under the Tube Deposit Weight. The Visual Tube Evaluation is determined by assigning demerits to the composition being tested according to the type of deposit which has formed on the tube. The tube is divided into for example, a flaked carbon deposit over a portion of the tube receives a demerit rating of 20. The demerit rating is then multiplied by the deposit weight per unit length. The deposit weight per unit length is determined by stripping the tube one inch at a time until the full length (10 inches) has been stripped. The total demerit rating is the sum of all ratings divided by 10 and is reported as visual tube evaluation. The demerit values assigned as according to the type of deposit are given in Table 7. The overall rating is the tube deposit weight plus the visual tube evaluation plus the filter screen deposits, all divided by two. An acceptable overall rating is less than 80, and preferably less than 60. Nevertheless, the composition of Example 63 is unsatisfactory because of the high acid number and the high viscosity change. The results of the Alcor High-Temperature Deposition Tests are given in Table 4. Also given are the Acid No. Change (as described heretofore). Clearly the only acceptable composition reported in Table 4 is that of Example 64 which contained two alkylated tertiary amines. The others, Examples 61, 62, and 63 failed the test.

Table 4 Results of Alcor High Temperature Deposition Tests" Parts by Weight Composition 61 64 Example No.

.Carboxylic Acid Ester 100 100 100 100 Phenyl-B-naphthylamine 1.0

4-(1.1,3,3-tetramethylbutyl) 1,5

Phenyl-B-naphthylamine N-4-( l ,1,3,3-tetramethylbutyl)- phenyl-N-B-naphthy1benzylamine 1.9 1.9 N,N-his-4-( 1.1 ,3,3-tetramethylbutyl)- "The composition 01' Example 64 is a composition of the instant invention. "A technical pentaerythritnl ester made from C C and C straight chain monocurhoxylie ucis.

TABLE 5 COMPOSITION Example No.

Carboxylic Acid Ester 100 100 100 N-4-(1.1.3,3-tetramethylbutyl)phenyl- 1.9 4.4

N-4-( l.1,3.3-tetramethylbutyl)phenylfl-naphthylamine N,N-bis-4-( l.1,3.3-tetramethylbutyl)- 2.5 4.4 phenylbenzvlnmine tetramethylbutyl )-diphenylamine Tricresyl phosphate 1.0 3-amino-l,2.4-triazole 0.05

PARTS BY WEIGHT 67 68 TABLE 5 Continued COMPOSITION PARTS BY WEIGHT Example No. 66 56 67 68 52 69 70 Corrosion, mg/cm Magnesium +0015 0.023 0.007 +0.0I0 0.015 0.015 +0.03) +0.0l5 +0.0l5 Aluminum 0.010 0.000 0.000 +0.0l0 0.000 0.000 0.015 0.000 0.000 Copper 0.023 0.078 0.078 0.052 0. 109 0.093 0.039 0.046 0.132 Iron +0.062 +0023 0.000 +0.054 0.000 0.000 +0.010 +0023 0.023 Silver 0.015 0.039 0.031 0.010 0.015 0.015 0.023 0.031 0.023 Total Acid No. Change, mg KOI-I/g 1.70 1.54 2.96 0.90 2.20 4.1 1.07 0.69 2.81 Viscosity Change (F), 3.6 21.9 44.3 20.1 20.6 37.4 19.7 17.2 406 Visual Sludge Rating Nil Moderate Moderate Nil Moderate Moderate Nil Heavy Moderate Data shown were taken from Table 3. "'A technical pentaerythritol ester made from C C and C straight chain monocarboitylic TABLE 6 COMPOSITION Example No. 61" 62" 71 63 72 73 74 64" Carboxylic Acid Ester" 100 100 I00 100 100 100 100 I00 Phenyl-Bmaphthylamine 1.0 N-4-( l l ,3,3'tetramethylbutyl)- phenyl- B-naphthylamine 1.5 1.5 4,4-( l ,l ,3,3-tetramethylbutyl diphenylamine 2.0 .0 2.0 N-4-( 1,1 ,3,3-tetramethylbutyl)- phenyl- N-B-naphthylbenzylamine 1.9 1.9 1.9 N,N-bis-4-(1,1,3,3 tetramethylbutyhphenylbenzylamine 2.5 2.5 Tricresyl phosphate 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Test Temperature, "F 550 550 550 550 550 550 550 550 Tube Deposits Weight, mg 398.5 18.6 90.9 22.0 24.9 32.0 40.6 16.0 Tube Deposit Rating 140.0 133.1 86.6 58.0 70.0 105.9 66.6 26.8 Filter Screen Deposits. mg 39.3 62.7 59.2 22.4 21.8 23.2 14.2 19.2 Overall Deposit Rating 288.9 107.2 118.3 51.2 58.3 80.5 60.7 31.0 (Cleanliness) Acid No. Change, mg KOH/g 8.9 12.2 7.9 13.2 8.2 2.4 1.01 1.15 Viscosity Change (100F), 172 334 213 62.0 419 97.5 40.3 14.5

"'Data shown were taken from Table 4.

"*A technical petttaerythritol ester made from C C and C straight chain monocarboxylic acids.

Table 7 DEPOSIT DESCRIPTION AND DEMERIT VALUES USED FOR NUMERICALLY DESCRIBING DEPOSITS Type of Demerit Deposit Degree Description Rating Flaked Carbon Carbonaceous coating that cannot 20 be removed by wiping with a rag. Broken blisters, peeling. Heavy Over 3/64-inch in thickness. Moderate Ranges from l/64-inch to less than 3/64-inch in thickness. Light Ranges from just covering to less than l/64-inch in thickness. Blistered Same as for flaked carbon 17 Carbon blistered, bubbled.

Heavy Same as for flaked carbon. Moderate Same as for flaked carbon. Light Same as for flaked carbon. Crinkled Same as for flaked carbon, 14

Carbon ridged, not smooth.

Heavy Same as for flaked carbon. Moderate Same as for flaked carbon. Light Same as for flaked carbon. Smooth Same as for flaked carbon, l 1

Carbon smooth coating.

Heavy Same as for flaked carbon. Moderate Same as for flaked carbon. Light Same as for flaked carbon. Sludge Shiny, oily emulsion of carbon 8 and oil. Can be wiped off with a rag. Heavy Approx. l/16-inch thick. Moderate Approx. l/32inch thick.

Light Just covering. Varnish Varnish or lacquer-like coating, 5

shiny. Clean Clean no deposit. 0

Examples 65-74 The general procedure of Examples 47-60 was repeated; however, said procedure was modified in these Examples (Examples 6574) by including the additives shown in Tables and 6 in the amounts shown for the respective Examples in said Tables 5 and 6 rather than the additives of Examples 47-60. The results obtained in Examples 6574 are presented in Tables 5 and 6. For the purpose of comparison, the results of certain Examples (i.e., Examples 52, 56, 60, 61, 62, 63, and 64) which were reported in Table 3 or Table 4 are repeated in Table 5 or Table 6.

Corrosion Oxidation test results shown in Table 5 for Example 65 indicates that increasing the antioxidant concentration to the combined inhibitor level used in Example 60 lowered the viscosity increase. However, the higher inhibitor concentration produced an increased level of sludging, compare Example 65 with Example 48 (Table 3). Likewise, increasing the inhibitor concentration in Example 66 to the combined inhibitor level employed in Example 60 not only increased the amount of sludging, but resulted in a significantly higher viscosity increase in Corrosion- Oxidation tests, compare Example 49 (Table 3) with Example 66. A similar result was observed with the antioxidants of Examples 52 and 56 shown in Tables 3 and 5. In none of the examples shown in Table 5 was the effectiveness of a single antioxidant, regardless of concentration, equivalent to the performance obtained by the combined antioxidants of the present invention.

An examination of the overall deposit ratings obtained from Alcor High-Temperature Deposition Tests shown in Table 6 clearly shows that the improvement in cleanliness obtained as a result of alkylation (Example 62 versus Example 61 and subsequent N- substitution (Example 63 versus Example 62) of the parent secondary amine.

Results shown for Examples 61, 62 and 71 represent prior art while those for Example 63 and 72 are illustrative of the improvement in cleanliness afforded by additives of the current invention.

The improvement in oxidation stability and cleanliness obtained by the combination of antioxidants of the present invention is clearly evident by an examination of the results shown in Table 6 for Examples 74 and 64 versus that illustrated by the prior art of Example 73 which does not contain a tertiary amine. A comparison of the oxidation stability and overall deposit ratings obtained with Examples 73 and 74 clearly shows the improvement obtained by the use of the combination of an alkylated secondary amine and a tertiary amine (Example 74) selected in accordance with the teachings of the Summary or Embodiment A-l versus that obtained by two alkylated secondary amines (Example 73). Likewise, the performance of two tertiary amines (Example 64) selected in accordance with the teaching of Embodiment A was superior to the combination of a tertiary amine and an alkylated secondary amine (Example 74).

In conclusion, as the foregoing examples show, a lubricant composition which is predominantly a carboxylic acid ester and which contains an alkylated secondary amine and an alkylated tertiary amine or, in the alternative, two alkylated tertiary amines selected as described in the Summary and Embodiments A and A supra, exhibits improved sludging characteristics over the prior art, and shows an acid No. change of less than 2, and a viscosity change of less than 25% in Corrosion- Oxidation Tests.

The lubricating composition of this invention as taught in the Summary and Embodiments A and A supra also exhibit excellent oxidation stability in High- Temperature Deposition Tests as evidenced by acid number and viscosity increase while exhibiting improved cleanliness over the prior art.

As used herein the term percent means part per hundred, and the term parts means parts .by weight unless otherwise defined where used.

A mole of a substance is that quantity of the substance which contains the same number of molecules of the substance as there are atoms in 12 grams of pure 12C.

We claim:

1. In a lubricant composition comprising major amounts of a carboxylic acid ester lubricant, the improvement comprising the presence of,

a. a secondary amine having the formula;

in which R and R are separately alkyl groups having 4-12 carbon atoms; and

b. a tertiary amine having the formula;

in which R is an alkyl group having 4-12 carbon atoms and R R and R are separately selected from the group consisting of CH C H iodine, bromine, chlorine, fluorine, nitro, and hydrogen, A is CCl CBr C1 or an alkylene group having about 1-7 carbon atoms, and R is hydrogen or an alkyl group having 4-12 carbon atoms, said secondary amine and said tertiary amine being present in an amount effective for improving oxidative stability of the ester base lubricant at temperatures up to at least 400F.

2. The composition of claim 1 in which R is C(CH CH C(CH 3. The composition of claim 1 in which R is 3)2 2 3)?.

4. The composition of claim 1 in which R is s)2 2 s)a- 5. The composition of claim 1 in which R, is C(CH CH C(CH 6. The composition of claim 1 in which A is CH CH 7. The composition of claim 1 in which R is C(CH CH C(CH 8. The composition of claim 1 in which A is CH 9. The composition of claim l in which R R and R are hydrogen.

10. The composition of claim 1 in which said compo sition contains 0.5-10 parts of a phosphorus-containing ester selected from the group consisting of tricresyl phosphate, triphenyl phosphate, cresyldiphenyl phosphate, xylyldiphenyl phosphate, triethyl phosphate, tributyl phosphate.

11. The composition of claim 1 in which said composition contains 0.1 part of an aminosubstituted 1,2,4- triazole.

12. The composition of claim 1 in which the carboxylic acid ester component of said composition is an ester derived from an aliphatic carboxylic acid having 3-18 carbon atoms and a polyol selected from the group consisting of trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, and neopentylglycol.

13. In a lubricant composition comprising major amounts of a carboxylic acid ester lubricant, the improvement comprising the presence of;

a. a first tertiary amine having the formula N l t in which R, is an alkyl group having 4-12 carbon atoms and R R and R are separately selected from the group consisting of CH C H iodine, bromine, chlorine, fluorine, nitro, and hydrogen, and A is CCl CBr C1 or an alkylene group having about 1-7 carbon atoms, and R is hydrogen or an alkyl group having 4-12 carbon atoms, said first tertiary amine and said second tertiary amine being present in an amount effective for improving oxidative stability of the ester base lubricant at temperatures up to at least 400F.

14. The composition of claim 13 in which R is C(CH CH C(CH 115. The composition of claim 13 in which R C(CH CH C(CH 16. The composition of claim. 13 in which R 3)2 2 3)3- 17. The composition of claim 13 in which R, 3)2 2 3)3- 118. The composition of claim 13 in which A CH CH 19. The composition of claim 13 in which R C(CH CH C(CH 20. The composition of claim 13 in which A is CH 21. The composition of claim 13 in which R R and R are hydrogen.

22. The composition of claim 13 in which said composition contains 0.5-10 parts of a phosphoruscontaining ester selected from the group consisting of tricresyl phosphate, triphenyl phosphate, cresyldiphenyl phosphate, xylyldiphenyl phosphate, triethyl phosphate and triisooctyl phosphate.

23. The composition of claim 13 in which said composition contains O.l part of an aminosubstituted 1,2,4- triazole.

in which R is an alkyl group having 4-12 carbon atoms and R is hydrogen or an alkyl group having 412 carbon atoms; and

b. a tertiary amine having the formula;

in which R and R are separately alkyl groups having 4-12 carbon atoms and R R and R are separately selected from the group consisting of CH C 11 iodine, bromine, chlorine, fluorine, nitro, and hydrogen, A is CCI CBr C1 or an alkylene group having about 1-7 carbon atoms, and R is hydrogen or an alkyl group having 4-12 carbon atoms, said secondary amine and said tertiary amine being present in an amount effective for improving oxidative stability of the ester base lubricant at temperatures up to at least 400F.

30. The composition of claim 29 in which R is C(CH3)2CH2C(CH3)8- 311. The composition of claim 29 in which A CH CH 32. The composition of claim 29 in which R 3)2 2 3)3- 33. The composition of claim 29 in which R C(CI-I CH C(CH 34. The composition of claim 29 in which R C(CH CH C(CH 35. The composition of claim 29 in which R C(CH CH C(CH 36. The composition of claim 29 in which A is CH 37. The composition of claim 29 in which R R and R are hydrogen.

38. The composition of claim 29 in which said composition contains 0.5l0 parts of a phosphoruscontaining ester selected from the group consisting of tricresyl phosphate, triphenyl phosphate, cresyldiphenyl phosphate, xylyldiphenyl phosphate, triethyl phosphate, tributyl phosphate and triisooctyl phosphate.

39. The composition of claim 29 in which said composition contains 0.1 part of an aminosubstituted 1,2,4- triazole.

40. The composition of claim 29 in which the carboxylic acid ester component of said composition is an ester derived from an aliphatic carboxylic acid having 3-18 carbon atoms and a polyol selected from the group consisting of trimethylopropane, pentaerythritol, dipentaerythritol, tripentaerythritol, and neopentylglycol. 

1. LUBRICANT COMPOSITION COMPRISING MAJOR AMOUNTS OF A CARBOXYLIC ACID ESTER LUBRICANT, THE IMPROVEMENT COMPRISING THE PRESENCE OF, A. A SECONDARY AMINE HAVING THE FORMULA,
 2. The composition of claim 1 in which R1 is C(CH3)2CH2C(CH3)3.
 3. The composition of claim 1 in which R2 is C(CH3)2CH2C(CH3)3.
 4. The composition of claim 1 in which R3 is C(CH3)2CH2C(CH3)3.
 5. The composition of claim 1 in which R4 is C(CH3)2CH2C(CH3)3.
 6. The composition of claim 1 in which A is CH2CH2.
 7. The composition of claim 1 in which R9 is C(CH3)2CH2C(CH3)3.
 8. The composition of claim 1 in which A is CH2.
 9. The composition of claim 1 in which R6, R7, and R8 are hydrogen.
 10. The composition of claim 1 in which said composition contains 0.5-10 parts of a phosphorus-containing ester selected from the group consisting of tricresyl phosphate, triphenyl phosphate, cresyldiphenyl phosphate, xylyldiphenyl phosphate, triethyl phosphate, tributyl phosphate.
 11. The composition of claim 1 in which said composition contains 0.1 part of an aminosubstituted 1,2,4-triazole.
 12. The composition of claim 1 in which the carboxylic acid ester component of said composition is an ester derived from an aliphatic carboxylic acid having 3-18 carbon atoms and a polyol selected from the group consisting of trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, and neopentylglycol.
 13. In a lubricant composition comprising major amounts of a carboxylic acid ester lubricant, the improvement comprising the presence of; a. a first tertiary amine having the formula
 14. The composition of claim 13 in which R1 is C(CH3)2CH2C(CH3)3.
 15. The composition of claim 13 in which R2 is C(CH3)2CH2C(CH3)3.
 16. The composition of claim 13 in which R3 is C(CH3)2CH2C(CH3)3.
 17. The composition of claim 13 in which R4 is C(CH3)2CH2C(CH3)3.
 18. The composition of claim 13 in which A is CH2CH2.
 19. The composition of claim 13 in which R9 is C(CH3)2CH2C(CH3)3.
 20. The composition of claim 13 in which A is CH2.
 21. The composition of claim 13 in which R6, R7, and R8 are hydrogen.
 22. The composition of claim 13 in which said composition contains 0.5-10 parts of a phosphorus-containing ester selected from the group consisting of tricresyl phosphate, triphenyl phosphate, cresyldiphenyl phosphate, xylyldiphenyl phosphate, Triethyl phosphate and triisooctyl phosphate.
 23. The composition of claim 13 in which said composition contains 0.1 part of an aminosubstituted 1,2,4-triazole.
 24. The composition of claim 13 in which the carboxylic acid ester component of said composition is an ester derived from an aliphatic carboxylic acid having 3-18 carbon atoms and a polyol selected from the group consisting of trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol and neopentylglycol.
 25. The composition of claim 13 in which the first tertiary amine is selected from the group consisting of N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenylbenzylamine N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-2-phenylethylamine N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-2-methylbenzylamine N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-4-methylbenzylamine N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-2-chlorobenzylamine N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-4-chlorobenzylamine N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-2,4-dichlorobenzylamine, N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-3,4-dichlorobenzylamine, N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl- Alpha , Alpha -dichlorobenzylamine, N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-2-fluorobenzylamine, N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-4-fluorobenzylamine, N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-4-nitrobenzylamine, and N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-2-phenylethylamine.
 26. The composition of claim 13 in which the second tertiary amine is N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Alpha -naphthylbenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Alpha -naphthyl-2-phenylethylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Alpha -naphthyl-2-methylbenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Alpha -napthyl-4-methylbenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Alpha -naphthyl-2-chlorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Alpha -napthyl-4-chlorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Alpha -naphthyl-2,4-dichlorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Alpha -napthyl-3,4-dichlorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Alpha -naphthyl- Alpha - Alpha -dichlorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Alpha -naphthyl-2-fluorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Alpha -napthyl-4-fluorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Alpha -naphthyl-4-nitrobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthylbenzylamines, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthyl-2-phenylethylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthyl-2-methylbenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthyl-4-methylbenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthyl-2-chlorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthyl-4-chlorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthyl-2,4-dichlorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthyl-3,4-dichlorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthyl- Alpha - Alpha -dichlorobenzylamine N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthyl-2-fulorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthyl-4-fluorobenzylamine, N-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthyl-4-nitrobenzylamine, or N-4-(,1,3,3-tetramethylbutyl)-phenyl-N- Beta -1-(1,1,3,3-tetramethylbutyl)- Beta -naphthylbenzylamine.
 27. A lubricant composition comprising: a. 100 parts of a carboxylic acid ester b. 0.5-10 parts of tricresyl phosphate; c. 0.5-8 parts of 4,4''-(1,1,3,3-tetramethylbutyl) diphenylamine; d. 0.5-10 parts of a tertiary amine selected from a group consisting of N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-N-Alpha -naphthylbenzylamine, and N,N-bis-4-(1,1,3,3-tetramethylbutyl)-phenyl-N- Beta -naphthylbenzylamine; and e. 0-0.5 parts of a member selected from a third group consisting of 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, benzotriazole, 5,5-methylene-bis-(1,2,3-benzotriazole), and a lower alkyl benzotriazole.
 28. A lubricant composition comprising: a. 100 parts of a carboxylic acid ester b. 0.5-10 parts of tricresyl phosphate; c. 0.5-8 parts of a secondary amine selected from the first group consisting of N-4-(1,1,3,3-tetramethylbutyl)phenyl- Alpha -naphthylamine, and N-4-(1,1,3,3-tetramethylbutyl)phenyl- Beta -naphthylamine; d. 0.5-10 parts of N,N-bis-4-(1,1,3,3-tetramethylbutyl) phenylbenzylamine, e. 0-0.5 parts of a member selected from a third group consisting of an amino-1,2,4-triazole, benzotriazole, 5,5-methylene-bis-(1,2,3-benzotriazole), and an alkyl benzotriazole.
 29. In a lubricant composition comprising major amounts of a carboxylic acid ester lubricant, the improvement comprising the presence of; a. a secondary amine having the formula;
 30. The composition of claim 29 in which R1 is C(CH3)2CH2C(CH3)3.
 31. The composition of claim 29 in which A is CH2CH2.
 32. The composition of claim 29 in which R3 is C(CH3)2CH2C(CH3)3.
 33. The composition of claim 29 in which R4 is C(CH3)2CH2C(CH3)3.
 34. The composition of claim 29 in which R5 is C(CH3)2CH2C(CH3)3.
 35. The composition of claim 29 in which R9 is C(CH3)2CH2C(CH3)3.
 36. The composition of claim 29 in which A is CH2.
 37. The composition of claim 29 in which R6, R7, and R8 are hydrogen.
 38. The composition of claim 29 in which said composition contains 0.5-10 parts of a phosphorus-containing ester selected from the group consisting of tricresyl phosphate, triphenyl phosphate, cresyldiphenyl phosphate, xylyldiphenyl phosphate, triethyl phosphate, triButyl phosphate and triisooctyl phosphate.
 39. The composition of claim 29 in which said composition contains 0.1 part of an aminosubstituted 1,2,4-triazole.
 40. The composition of claim 29 in which the carboxylic acid ester component of said composition is an ester derived from an aliphatic carboxylic acid having 3-18 carbon atoms and a polyol selected from the group consisting of trimethylopropane, pentaerythritol, dipentaerythritol, tripentaerythritol, and neopentylglycol. 